HER NAME IS SIA. She is one of the most promising singers to emerge on the music scene in the last few years. And Wednesday night at the 9:30 Club in Washington, D.C., she was one of two featured performers of the British musical act Zero Seven. The couple standing behind me didn’t know exactly what to make of her. “She’s, um, quirky,” said the man. “Yeah,” replied his date.

Quirky, however, is a serious understatement for this hilarious, audacious, unbridled singer. She talks half nonsense into the microphone, her funny-girl cheeks always bunched up by a great moon-sliver of teeth, and then with barely a pause she busts out a song with a voice the size of houses, buildings, the streets, and the neighborhood. One wonders if this is what is what it was like to see Bjork when she was still with the Sugar Cubes or, for an odd pairing, maybe a young, rascally Natalie Maines before she became important. It was that kind of thing: power and personality and a singular stage presence without any forewarning.